Load damping frame hitch for vehicles towing a trailer

ABSTRACT

A load-damping motor-vehicle frame-type trailer hitch attachable at its forward end to a vehicle frame and at its rearward end to the automobile bumper, with means to allow relative motion between the two points of connection. The hitch includes a compression means which absorbs forward thrust loads in advance of placing a load upon the bumper, in the case of conventional bumpers, or, in the case of an energy absorbing bumper, adds energy absorption capability, allows return of the bumper to its original position without damage to either the bumper or hitch and without degradation of the energy absorption characteristics of the combined mechanisms. The hitch is operable with or without other load damping devices, and within both returnable and nonreturnable ranges of operation. The hitch is particularly adaptable to use with energy absorption bumpers.

States Abromavage et a1.

LOAD DAMPING FRAME HITCH FOR VEHICLES TOWING A TRAILER Filed: June 3,1974 Appl. No.: 476,008

Related U.S. Application Data Division of Ser. No. 384,764, Aug. 1,1973.

U.S. Cl. 280/476 Int. Cl 860d 1/16 Field of Search 280/486, 487, 483

References Cited UNITED STATES PATENTS 3/1914 Voller et al.... 280/486 X2/1923 Novak 280/486 6/1927 Hawkins 280/486 11/1960 Keese 280/486 XAntici 280/487 X Primary Examiner-Leo Friaglia [57] ABSTRACT Aload-damping motor-vehicle frame-type trailer hitch attachable at itsforward end to a vehicle frame and at its rearward end to the automobilebumper, with means to allow relative motion between the two points ofconnection. The hitch includes a compression means which absorbs forwardthrust loads in advance of placing a load upon the bumper, in the caseof conventional bumpers, or, in the case of an energy absorbing bumper,adds energy absorption capability, allows return of the bumper to itsoriginal position without damage to either the bumper or hitch andwithout degradation of the energy absorption characteristics of thecombined mechanisms. The hitch is operable with or without other loaddamping devices, and within both returnable and nonreturnable ranges ofoperation. The hitch is particularly adaptable to use with energyabsorption bumpers.

PATENIEB FEB M975 SHEET 2 OF 2 LOAD DAMPING FRAME HITCH FOR VEHICLESTOWING A TRAILER This is a division, of application Ser. No. 384,764,filed Aug. 1, 1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention Motor vehiclehitches for use in pulling trailers. Conventionally, a ball hitch, usedin pulling trailers, is mounted either upon the motor vehicle bumper asa temporary attachment or the hitch is secured permanently either to thevehicle frame, or to both the frame and bumper. The hitch is suitablefor either permanent or temporary attachment.

2. Description of the Prior Art Prior art frame and bumper hitches weredeveloped in a period when bumpers were rigidly attached to the frame,and before energy absorbing characteristics became a major factor in thedesign of the rear ends of motor vehicles. Therefore, prior art makes noprovision for relative movement of the bumper in regard to the frame, orto the controlled absorption of loads applied to the hitch. The priorart uses springs to distribute and absorb transient loads, but does notinclude the concepts of relative motion between attachment points on thetow vehicle or the absorption of energy from sustained loads through aviscous damping device. Prior art frame hitches can only allow relativemotion between attachment points by permanent deformation of thestructural members.

SUMMARY OF THE INVENTION According to the present invention, a loaddamping hitch of the type used for the pulling of a trailer includes ahitch platform secured at its forward end to the vehicle frame andextending rearwardly of the frame. A coupling ball is mounted at therearward end of the hitch. A bracket is secured at its top to thevehicle bumper and extends downwardly to movably engage the hitchplatform. A shock absorbing means is supported upon the hitch platformintermediate the coupling ball and the forward end of the frame. As aresult, forward thrust of the ball, imposed by the compressive forces ofthe trailer as upon braking of the vehicle or rear impact are absorbedby the shock absorbing means.

The coupling ball may be mounted upon a housing which is slidable alongthe hitch platform and encloses a conventional shock absorber. Also, acombined compression spring and piston element may be used as the shockabsorber. In such cases, the rearward end of the hitch platform issuspended from a link attached to the vehicle bumper, the housingsliding or moving independently of the hitch platform or the bumper.Alternatively, the hitch platform itself may be pivoted atits forwardend to the bumper and at its rearward end which supports the couplingball, the hitch platform may extend through one or more open brackets.The shock means may be interposed between the forward end of the hitchplatform and the frame itself. In this later modification the entirehitch platform pivots longitudinally in response to compressive forcesof the trailer.

The advantages of the present invention over prior art are:

1. Independent and redundant load paths are provided for the absorptionof longitudinally compression loads.

2. The tow vehicle is given protection from damage resulting from rearimpact loads on the trailer.

3. Relative movement between the bumper and frame are permitted.

4. Hitch ball forces are absorbed other than by transmittal to the towvehicle.

5. Means are provided to establish a threshold of loading prior toactuation of the load damping mechanism.

6. Longitudinal compression loads, up to predetermined limits, can beabsorbed without loading the vehicle bumper.

7. Hitch can be used on vehicles equipped with either rigid or energyabsorbing rear bumpers.

8. Loads beyond normal towing loads can be absorbed without permanentdeformation and the mechanism reset for continued operation byresumption of longitudinal tension loads.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation, showingthe hitch platform mounted at its forward end to the vehicle frame andsupporting a coupling ball housing which is slidable upon the hitchplatform and independently of the link connection of the hitch platformto the vehicle bumper;

FIG. 2 is a modification, showing a hitch ball being mounted upon aslidable platform which is supported by links at the rearward end of thehitch platform and showing, also, the over-ride link interconnecting thevehicle bumper and the rearward end of the hitch platform;

FIG. 3 is a further modification, showing pivotal connection of theforward end of the hitch platform to the vehicle frame;

FIG. 4 is a top plan, showing an adapter bracket used to connect theforward end to the hitch platform to the vehicle frame as in FIGS. 1 and2.

FIG. 4A is a side elevation of an adapter bracket as in FIG. 4; and

FIG. 5 is a top plan, showing an A frame hitch platform as in FIG. 3.

DESCRIPTION OF THE. PREFERRED EMBODIMENTS In FIG. 1 there is shown an Aframe hitch platform 10, secured by means of adapters 20 (refer also toFIGS. 4 and 4A), machine bolts or the like 26, 28, 22 and 24 to thevehicle frame. In FIG. 1, the rearward end of hitch platform 10converges into the platform 40 which in turn supports platform slide 52,such that the platform slide 52, including coupling ball support 16 andhitch ball 74 may move longitudinally with respect to open bracket 50which is rigidly attached to platform 40. Spring latch 42 which may besecured by machine bolts 46 and 48 to platform 40 engages ball platformretainer 44. A shock absorbing element 56, including movable rod 58 maybe secured in the rear end of the platform slide 52 by means of nut andnut 72. Also, a compression spring 54 may encircle the shock absorbingelement 56 so as to abut plate 174 at its forward end and the rear ofthe housing at its other end. Plate 174 is rigidly attached to platform40. Bumper support bracket 34 is secured to the vehicle bumper 32 bymeans of bolts 76, 78 or the like and includes a pivoting link 36pivoted at its top by means of bolt 35 and its bottom by means of bolt38 extending through the platform 40.

As will be apparent, coupling ball 74 center of gravity is supportedmedially on the top and bottom of the vehicle bumper 32 and is held inits rearwardly extended position by the action of compression spring 54.

If the trailer (not illustrated) is backed into a solid object, thespring latch 42 is disengaged, allowing the recoil spring 54 and shockabsorber 56 to absorb initial impact. Similarly, if the compressiveforce exceeds the design load, the hitch ball during towing may forcethe spring latch open. As a result, the shock absorber absorbs aninitial impact, then permits the ball platform 16 to return slowly tothe rearwardly extended position illustrated in FIG. 1. This is designedto prevent damage to the trailer, the forward attachment of the tongueor to the bumper itself. However, under normal operating or towingconditions the hitch functions as a frame hitch.

In the modification illustrated in FIG. 2, the forward end of A framehitch platform is secured by means of adapter bracket 20 havingidentical bolt or the like connections 22, 24, 26 and 28. A housing 31is defined at the rearward end of the hitch platform 40', so as tosupport a pair of swinging links 100 and 106, secured to the hitchplatform 40' at the bottom by means of bolts 104 and 94 and secured attheir tops by means of bolts 102 and 110, extending through the tonguesupport platform 14. A platform stop secured to the underside of housing31 prevents excessive rearward movement of the platform 14. Housing 31at its top supports a spring latch 112 held by bolts 116 and 118 in theform of downwardly depending shoulder 114 which engages the forward end120 of platform 14 as a lock. A conventional shock absorbing element 96including piston 98 may be pivoted in the housing 31 as at 97, extendingforwardly via a clevis arrangement to bolt 122 fixed to bracket 124which is secured to platform 14. Link 90 is pivoted at its upper end asat 92 to bumper bracket 88. Bracket 88 may be secured to the bumpermid-portion by means of plate 82 and bolts 84 and 86. Link 90 at itsbottom end is pivoted in bolt 94 at the rear end of the hitch platform40'.

When starting to pull a trailer, ball platform 14 moves backwardly intolocked position against platform stop 15. If the trailer is backed intoa solid object, the spring latch 114-120 disengages and permits the ballplatform 14 to pivot forwardly, absorbing the shock. This preventsdamage to the trailer or the frame connection or to the bumper itself.

In the FIG. 3 modification, A frame hitch platform 10 (refer also toFIG. 5) includes at its forward end platform 144 supporting stop lock134by means of bolts 146 and 148. Forward link 130 interconnects theframe bracket 126 pivoting stud 128 and pivoting stud 132, extendingthrough the stop lock 134. A conventional shock absorber 136 may bepivoted rearwardly in stud 140, extending through shock mounted bracket142 secured to the frame 30. A frame to hitch platform slide 150 may besecured to the frame by means of bolts 152 or the like and may includelower horizontal portions 164, 166 secured by bolts 158 for slidablyengaging the coupling ball support piece 141. A sliding bumper adapterbracket 151 may be secured to plate 168 by means of bolts 170 and 172.

When the car is towing the trailer, pivoting linkage is secured againststop lock shoulder at the forward end of the hitch platform 10 arms.Tension spring 138 and shock absorber 136 are used to maintain the framehitch in normal position and absorb compressive shock if the trailer isbacked into a solid object.

As will be apparent, the hitch and shock absorbing elements can bedesigned to withstand a predetermined load after which the additionalload will be transferred either to the frame or the automobile bumper.For example, a pair of shock absorbing elements in the FIG. 3configuration may be employed upon individual arms to absorb 800 poundsof compression per arm. Any loads in addition to 1,600 pounds, would beplaced directly on the hitch connection itself. Also, in the FIGS. 1 and2 modification, a load exceeding the compressive elements would betransferred first to the frame without encumbering or loading theautomobile bumper.

Manifestly, variations in sliding support of the hitch platform andcompressive elements may be employed without departing from the spiritof the invention.

We claim:

1. A vehicle frame hitch of the type used for hitching and pullingtrailers comprising:

A. a hitch platform movably attached at its forward end to the vehicleframe and slidably supported by brackets extending downwardly from thevehicle frame and bumper;

B. a hitch ball secured to the rear end of said hitch platform;

C. a bumper adapter bracket secured to the vehicle bumper and slidablyengaging said hitch platform; and

D. tension means connected between the forward end of said hitchplatform and brackets secured to the vehicle frame rearwardly of saidforward end.

2. A vehicle frame hitch of the type used for hitching and pullingtrailers as claimed in claim 1, said hitch platform being supported atits forward ends by pivoting links and said tension means.

3. A vehicle frame hitch of the type used for hitching and pullingtrailers as claimed in claim 1, said hitch platform being of A frameconfiguration and connected at its open ends to brackets affixed to saidvehicle frame and at its rear end converging together beneath said hitchball mount.

1. A vehicle frame hitch of the type used for hitching and pullingtrailers comprising: A. a hitch platform movably attached at its forwardend to the vehicle frame and slidably supported by brackets extendingdownwardly from the vehicle frame and bumper; B. a hitch ball secured tothe rear end of said hitch platform; C. a bumper adapter bracket securedto the vehicle bumper and slidably engaging said hitch platform; and D.tension means connected between the forward end of said hitch platformand brackets secured to the vehicle frame rearwardly of said forwardend.
 2. A vehicle frame hitch of the type used for hitching and pullingtrailers as claimed in claim 1, said hitch platform being supported atits forward ends by pivoting links and said tension means.
 3. A vehicleframe hitch of the type used for hitching and pulling trailers asclaimed in claim 1, said hitch platform being of ''''A'''' frameconfiguration and connected at its open ends to brackets affixed to saidvehicle frame and at its rear end converging together beneath said hitchball mount.